Basic functionality to add coordinator-only nodes (read-only nodes that do not add dbroot of other nodes)

cmapi/cmapi_server/controllers/endpoints.py

@@ -913,16 +913,20 @@ class ClusterController:
         config = request_body.get('config', DEFAULT_MCS_CONF_PATH)
         in_transaction = request_body.get('in_transaction', False)
         read_only = request_body.get('read_only', False)
+        add_other_nodes_dbroots = request_body.get('add_other_nodes_dbroots', True)
 
         if node is None:
             raise_422_error(module_logger, func_name, 'missing node argument')
 
+        if not read_only and ('add_other_nodes_dbroots' in request_body):
+            raise_422_error(module_logger, func_name, 'add_other_nodes_dbroots is only valid when read_only is true')
+
         try:
             if not in_transaction:
                 with TransactionManager(extra_nodes=[node]):
-                    response = ClusterHandler.add_node(node, config, read_only)
+                    response = ClusterHandler.add_node(node, config, read_only, add_other_nodes_dbroots)
             else:
-                response = ClusterHandler.add_node(node, config, read_only)
+                response = ClusterHandler.add_node(node, config, read_only, add_other_nodes_dbroots)
         except CMAPIBasicError as err:
             raise_422_error(module_logger, func_name, err.message)
 

cmapi/cmapi_server/handlers/cluster.py

@@ -50,7 +50,7 @@ def toggle_cluster_state(
     broadcast_new_config(config, distribute_secrets=True)
 
 
-class ClusterHandler():
+class ClusterHandler:
     """Class for handling MCS Cluster operations."""
 
     @staticmethod
@@ -143,6 +143,7 @@ class ClusterHandler():
     def add_node(
         node: str, config: str = DEFAULT_MCS_CONF_PATH,
         read_only: bool = False,
+        add_other_nodes_dbroots: bool = True,
     ) -> dict:
         """Method to add node to MCS CLuster.
 
@@ -151,8 +152,10 @@ class ClusterHandler():
         :param config: columnstore xml config file path,
                        defaults to DEFAULT_MCS_CONF_PATH
         :type config: str, optional
-        :param read_only: add node in read-only mode, defaults to False
+        :param read_only: add node in read-only mode (not starting write engine), defaults to False
         :type read_only: bool, optional
+        :param add_other_nodes_dbroots: for read-only nodes, whether to add dbroots of other nodes
+        :type add_other_nodes_dbroots: bool, optional
         :raises CMAPIBasicError: on exception while starting transaction
         :raises CMAPIBasicError: if transaction start isn't successful
         :raises CMAPIBasicError: on exception while adding node
@@ -170,11 +173,15 @@ class ClusterHandler():
 
         response = {'timestamp': str(datetime.now())}
 
+        if not read_only and add_other_nodes_dbroots is not True:
+            raise CMAPIBasicError('add_other_nodes_dbroots is only valid when read_only is true')
+
         try:
             add_node(
                 node, input_config_filename=config,
                 output_config_filename=config,
                 read_only=read_only,
+                add_other_nodes_dbroots=add_other_nodes_dbroots,
             )
             if not get_dbroots(node, config):
                 if not read_only:  # Read-only nodes don't own dbroots

cmapi/cmapi_server/node_manipulation.py

@@ -64,6 +64,7 @@ def add_node(
     output_config_filename: Optional[str] = None,
     use_rebalance_dbroots: bool = True,
     read_only: bool = False,
+    add_other_nodes_dbroots: bool = True,
 ):
     """Add node to a cluster.
 
@@ -102,7 +103,7 @@ def add_node(
                 _add_WES(c_root, pm_num, node)
             else:
                 logging.info('Node is read-only, skipping WES addition.')
-                _add_read_only_node(c_root, node)
+                _add_read_only_node(c_root, node, add_other_nodes_dbroots)
 
             _add_DBRM_Worker(c_root, node)
             _add_Module_entries(c_root, node)
@@ -113,6 +114,7 @@ def add_node(
                     _rebalance_dbroots(c_root)
                     _move_primary_node(c_root)
 
+            if read_only and add_other_nodes_dbroots:
                 update_dbroots_of_readonly_nodes(c_root)
     except Exception:
         logging.error(
@@ -1020,8 +1022,8 @@ def _add_WES(root, pm_num, node):
     etree.SubElement(wes_node, "Port").text = "8630"
 
 
-def _add_read_only_node(root: etree.Element, node: str) -> None:
+def _add_read_only_node(root: etree.Element, node: str, add_other_nodes_dbroots: bool = True) -> None:
-    '''Add node name to ReadOnlyNodes if it is not already there'''
+    '''Add node name to ReadOnlyNodes if it is not already there, with attribute'''
     read_only_nodes = root.find('./ReadOnlyNodes')
     if read_only_nodes is None:
         read_only_nodes = etree.SubElement(root, 'ReadOnlyNodes')
@@ -1031,9 +1033,11 @@ def _add_read_only_node(root: etree.Element, node: str) -> None:
                 logging.warning(
                     f"_add_read_only_node(): node {node} already exists in ReadOnlyNodes"
                 )
+                n.set("add_other_nodes_dbroots", str(add_other_nodes_dbroots).lower())
                 return
-
+    node_elem = etree.SubElement(read_only_nodes, "Node")
-    etree.SubElement(read_only_nodes, "Node").text = node
+    node_elem.text = node
+    node_elem.set("add_other_nodes_dbroots", str(add_other_nodes_dbroots).lower())
 
 
 def _add_DBRM_Worker(root, node):
@@ -1202,17 +1206,28 @@ def get_pm_module_num_to_addr_map(root: etree.Element) -> dict[int, str]:
 def update_dbroots_of_readonly_nodes(root: etree.Element) -> None:
     """Read-only nodes do not have their own dbroots, but they must have all the dbroots of the other nodes
     So this function sets list of dbroots of each read-only node to the list of all the dbroots in the cluster
+
+    There is a special sub-mode of read-only nodes: coordinator nodes, they don't add dbroots of other nodes.
+    They are identified by the add_other_nodes_dbroots="false" attribute.
     """
-    nc = NodeConfig()
+
     pm_num_to_addr = get_pm_module_num_to_addr_map(root)
-    for ro_node in nc.get_read_only_nodes(root):
+    read_only_nodes = root.find('./ReadOnlyNodes')
+    if read_only_nodes is None:
+        return
+    for n in read_only_nodes.findall("./Node"):
+        add_dbroots = n.get("add_other_nodes_dbroots", "true").lower() == "true"
+        if not add_dbroots:
+            logging.info(f"Not adding dbroots of other nodes to {n.text} because it is a coordinator node")
+            continue
+
+        ro_node = n.text
         # Get PM num by IP address
         this_ip_pm_num = None
         for pm_num, pm_addr in pm_num_to_addr.items():
             if pm_addr == ro_node:
                 this_ip_pm_num = pm_num
                 break
-
         if this_ip_pm_num is not None:
             # Add dbroots of other nodes to this read-only node
             add_dbroots_of_other_nodes(root, this_ip_pm_num)